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Hurricane Maria Discussion Number  39
NWS National Hurricane Center Miami FL       AL152017
500 PM EDT Mon Sep 25 2017

Maria's coldest cloud tops and deepest convection continue to be
over the far eastern and northern portions of the circulation, but a
small area of convection has re-developed near the center this
afternoon.  SFMR data from a NOAA aircraft investigating Maria
indicate that the maximum winds remain near 70 kt, and that the
area of hurricane-force winds extends about 90 nm from the
center over the eastern semicircle.

Maria continues its slow northward trek.  A slow northward motion
should continue for another couple of days as Maria moves around
the western side of a subtropical ridge over the western Atlantic,
but the forward speed is atypically slow due to ridging over the
northeastern United States.  A deep mid-latitude trough will be
moving into the northeastern U.S. late this week, which is
expected to cause Maria to accelerate northeastward after 72 hours.
The track guidance remains tightly clustered through the first 48 to
72 hours, but there are still some speed differences beyond that
time.  The NHC forecast track lies near the middle of the guidance
envelope through 72 h, and is close to the various consensus aids
late in the period.

Cooler waters, moderate westerly shear, and dry air are expected
to cause a gradual decrease in wind speed over the next few days.
However, Maria is likely to remain a strong cyclone throughout the
forecast period.  Extratropical transition is likely to begin in
96 h with Maria completing this process near the end of the
forecast period.

KEY MESSAGES:

1. Maria is forecast to continue moving northward, paralleling the
U.S. east coast, and it is likely that some direct impacts will
occur along portions of the North Carolina coast beginning Tuesday,
where a Tropical Storm Warning is in effect.

2. Storm surge flooding, especially along the sound side of the
North Carolina Outer Banks, is possible beginning on Tuesday, and a
Storm Surge Watch has been issued for portions of eastern North
Carolina.

3. Swells generated by Maria are affecting much of the
east coast of the United States from Florida through southern New
England.  These swells are also affecting Bermuda, Puerto Rico, the
northern coast of Hispaniola, the Turks and Caicos Islands, and
the Bahamas.  These swells are likely to cause life-threatening surf
and rip current conditions.  Please consult products from your local
weather office for more information.



FORECAST POSITIONS AND MAX WINDS

INIT  25/2100Z 31.7N  73.1W   70 KT  80 MPH
 12H  26/0600Z 32.5N  73.2W   65 KT  75 MPH
 24H  26/1800Z 33.5N  73.2W   65 KT  75 MPH
 36H  27/0600Z 34.4N  73.1W   60 KT  70 MPH
 48H  27/1800Z 35.3N  72.8W   60 KT  70 MPH
 72H  28/1800Z 36.3N  69.6W   60 KT  70 MPH
 96H  29/1800Z 38.8N  60.5W   60 KT  70 MPH
120H  30/1800Z 45.0N  45.0W   60 KT  70 MPH...POST-TROP/EXTRATROP

$$
Forecaster Brown

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